AUG 2013

EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.

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22 EW REFRACTIVE SURGERY August 2013 Corneal transplantation: Impact of the widening pool of prior refractive surgery donors by Maxine Lipner EyeWorld Senior Contributing Writer P atients who have undergone refractive surgery are here to stay and are potentially part of the corneal donor pool, according to Mark A. Terry, MD, director of corneal services, Devers Eye Institute, and professor of clinical ophthalmology, Oregon Health & Science University, Portland, Ore. "There have been millions of LASIK patients in the United States, and a good portion of those patients will become donors in the future," Dr. Terry said. Already corneas from those who have undergone LASIK, PRK, and even RK are becoming a part of the pool for partial-thickness transplants, but are not eligible for traditional transplants. "Right now the Eye Bank Association of America does not allow a person who has had LASIK, PRK, or RK or who has any corneal scars to be a donor for a full-thickness corneal transplant," Dr. Terry said. "The reason is because if you transplant an eye that's got a scar, you're putting a defective cornea into the recipient, and if you try and do a full-thickness penetrating keratoplasty from a donor who has had LASIK, the surface can fall apart." Refractive impact To this point, however, the impact has been limited, observed David B. Glasser, MD, assistant professor of ophthalmology, Johns Hopkins University School of Medicine; in practice, Patapsco Eye MDs, Columbia, Md.; and chair elect, Eye Bank Association of America. "In 2012 there were approximately 115,000 tissues recovered and about 30,000 or so of the donor tissues couldn't be released for one reason or another," Dr. Glasser said. "About 12,000 were disqualified due to a problem with the tissue; only 298 (0.3%) were disqualified due to prior refractive surgery." Kenneth S. Himmel, MD, cornea specialist, Eye Associates of New Mexico, Albuquerque, N.M., and medical director, New Mexico Lions Eye Bank, explained that there is currently no shortage. "Of the total tissues that were released for transplantation, 4,900 of these were never used," he said. Still, in the future, it might be a bigger issue, Dr. Himmel noted. "As prior refractive surgery patients reach an age where they may be more likely to donate tissue, this may have a potentially bigger impact on the supply," he said. "Also, you can't always tell that the patient had prior refractive surgery, so it's quite possible that some of the tissue that was released may have been from patients who had refractive surgery and it wasn't able to be detected." Dr. Glasser agreed that this is a possibility. "There are a couple of anecdotal reports in the literature of tissue that, to the surprise of the surgeon, delaminated into an anterior and posterior section because the donor had prior LASIK that was missed," he said. However, he thinks that the eye banks catch the vast majority of these. New life for LASIK tissue John E. Sutphin, MD, Luther and Ardis Fry professor and chairman, Department of Ophthalmology, University of Kansas Medical Center, Prairie Village, Kan., noted that the move toward partial-thickness transplantation procedures has given new life to refractive tissue. "Now with the change in procedures moving toward lamellar-type surgery, donors who've had LASIK or PRK can still be used for deep transplants or endothelial transplants like DMEK (Descemet's membrane endothelial keratoplasty) and DSAEK (Descemet's stripping automated endothelial keratoplasty)," Dr. Sutphin said. "The tissue still has value." Dr. Terry, who developed the endothelial keratoplasty technique here in the U.S., is the one who originally urged the medical advisory board to update the eye bank rules on this. "What I recommended was that they change the rules restricting these prior refractive surgery donors from use in 'corneal transplantation' so that these tissues would be allowed for endothelial keratoplasty. By changing the old rules, we could then transplant the healthy back part of the cornea and utilize all of these tissues that were coming in with LASIK and PRK," he said. He subsequently published two papers showing that there is no difference in the results of using corneas from a donor with previous LASIK, PRK, or even RK, when this is used for DLEK (deep lamellar endothelial keratoplasty), DSEK (Descemet's stripping endothelial keratoplasty), and DMEK.1,2 Still, some adaptation may be needed. With prior refractive tissue, the preparation may be a bit different, Dr. Sutphin noted. "It is best if you know they've had LASIK because you would adjust the parameters that you use to prepare the tissue," he said. "The cornea will be thinner so you may need to use a different kind of device or different depth of device in making the cuts." Also, he said the original LASIK flap might slip while you're trying to prepare the button to be used for DSEK or DMEK. Dr. Glasser said it is up to eye bank medical directors to determine whether they will use previous refractive surgery tissue. "That's a bank-by-bank and ultimately a surgeon-by-surgeon decision," he said. "I personally wouldn't hesitate to take tissue from a patient who previously had LASIK and use it for endothelial keratoplasty, but some surgeons would." Some have concerns as to whether the endothelial cells are OK, but he feels that's not continued on page 24 DMEK with 20/20 results from a donor with LASIK An in place DSAEK in a pseudophakic patient Source: Mark A. Terry, MD Source: John D. Sutphin, MD

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